Submitted to: American Phytopathological Society
Publication Type: Abstract Only
Publication Acceptance Date: March 26, 2004
Publication Date: N/A
Technical Abstract: Tagetitoxin is a phytotoxin composed of two six-membered rings, one composed of five carbons and one sulfur atom and the other composed of five carbons and one oxygen atom. Both rings have a nitrogen moiety attached. Tn5 mutagenesis was used to identify genes required for tagetitoxin production by Pseudomonas syringae pv. tagetis EB037, a strain originally isolated from common ragweed (Ambrosia artemisiifolia L.). Mutants with Tn5 inserts in DNA regions that have homology with genes that encode for asparagine synthetase , iron transport systems, sulfate adenylate transferase, and global regulators were identified from the 17 nontoxigenic mutants produced. The asparagine synthetase mutant was not an asparagine auxotroph nor was toxin restored with the addition of free amino acids to the culture media. The sulfate adenylate transferase mutant did not grow in minimal media, however normal growth and toxin production were restored with the addition of cysteine to the growth media. Interestingly, the addition of sulfite or sulfide as a sulfur source restored normal growth in minimal media but did not restore toxin production. Further characterization of these mutants is underway.